The Last Seraphim's Sanctuary, also known as the LSS or the sissy revival machine, is a device that can use Soul Charge from a Soul Star placed in its slot to revive dead people. It seems to repair itself when broken.
When the first Ciro died, Al put his corpse along with Mili's into the LSS at the same time, it is unclear weather they were combined somehow or if Mili was destroyed completely. rather than return as he was ciro became a female blood mage . Cherish's Soul Star was in the slot powering this.
Immediately after revival, while confused, Ciro mentions from her past memories that there should have had been seven of the LSS.
By putting Slog's corpse into the LSS and Ciro's Astral Influx into the slot, Slog was successfully revived from the dead near the end of Chapter 3. Many rejoiced.
Polydectes possesses two Modified LSS, he uses these to modify the shape and form of various Illborn. He also plans to use his LSS's for experiments, and further expand his research on Illbirth, Illborn, and the various components that compose a Soul, and it's link to a vessel